1. Field of this Invention
This invention relates to a process for covalent surface modification of macromolecular substances, in particular for hydrophilizing the surfaces of natural or synthetic macromolecular substrates and for giving them ionic properties. In the case of plastics, for example, this should improve their printability and their suitability for being painted and glued. This invention further relates to new azide and diazo compounds which permit surface modification and to a process for the fabrication of such compounds.
2. Prior Art
It is already known that the properties of polymer surfaces may be modified by grafting hydrophilic, hydrophobic or ionic monomers to the base polymers or by the subsequent application of soluble polymers, e.g. polyacrylic acid, to the polymer surfaces, thus causing cross-linking. Major changes in surface properties may also be achieved by chemical reactions at the polymer surface, e.g. by chlorosulfonation, oxidation, etc. Furthermore low-molecular compounds may be bonded to the surface by the effect of plasma or radiation-induced polymerization.
The disadvantage of these processes is, however, that they are specific to a particular base material and may only be applied to other materials in modified form. This makes it difficult to apply these methods to moldings consisting of several base polymers. In addition, unsatisfactory results are obtained, in particular with hydrophobic polyolefines such as polyethylene and polypropylene, process costs are high, reaction times long and subsequent treatment is necessary. A further drawback is that in many cases the base material became partially chemically decomposed with the result that fragments could easily be removed from the molding. For this reason most of these processes are used on an industrial scale only for the treatment of films.